fix(nicoluaj): avoid overriding customization params (#12859)

themes/nicoulaj.zsh-theme

@@ -12,12 +12,12 @@
 # ------------------------------------------------------------------------------
 
 # Customizable parameters.
-PROMPT_PATH_MAX_LENGTH=30
-PROMPT_DEFAULT_END=❯
-PROMPT_ROOT_END=❯❯❯
-PROMPT_SUCCESS_COLOR=$FG[071]
-PROMPT_FAILURE_COLOR=$FG[124]
-PROMPT_VCS_INFO_COLOR=$FG[242]
+PROMPT_PATH_MAX_LENGTH=${PROMPT_PATH_MAX_LENGTH:-30}
+PROMPT_DEFAULT_END=${PROMPT_DEFAULT_END:-❯}
+PROMPT_ROOT_END=${PROMPT_ROOT_END:-❯❯❯}
+PROMPT_SUCCESS_COLOR=${PROMPT_SUCCESS_COLOR:-$FG[071]}
+PROMPT_FAILURE_COLOR=${PROMPT_FAILURE_COLOR:-$FG[124]}
+PROMPT_VCS_INFO_COLOR=${PROMPT_VCS_INFO_COLOR:-$FG[242]}
 
 # Set required options.
 setopt promptsubst